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176                                ALASKAN GLACIER STUDIES
of 102 inches in 1882 and 1883, 110 inches in 1884, 102 inches in 1885, and 140 inches in 1886. Prom 1890 to 1899 inclusive there are no records; but from 1900 to 1909 the precipitation has been fairly regular, the highest being 88 inches, the lowest 73 inches.
At Killisnoo, 40 miles northeast of Sitka, records from 1890 to 1905 give a range between 48 inches and 72 inches. At Fort Liscum, near Valdez, 250 miles northwest of Yakutat Bay, records for seven years between 1901 and 1909 show a variation between •56 inches in 1904 and 91 inches in 1907. Other records are even more fragmentary. Indeed, some of the variations are so remarkable that one is almost tempted to question their accuracy, as when the Sitka precipitation the year before the temporary cessation of records (1886) leaped up to 140 inches, and the records at Chilkat, which though kept for only two years give 39 inches for 1884 and only 11 inches in 1885.1
The precipitation records, though showing remarkable variations at a given station, .fail to show similar variations for the same years at other stations. Thus we must assume that whatever variations there are, in those years where comparisons are possible, are local, not general. Unfortunately this comparison cannot be carried very far, though it may be made in some cases. For example, the year (1885) when Chilkat had a precipitation of only 11 inches, Sitka had 102 inches! The highest precipitation at Sitka since 1900 is 88 inches (in 1901 and 1902), but in these same years the nearby station of JSillisnoo had only 55 and 45 inches respectively, both below the average precipitation, "which is 56 inches. The highest recorded precipitation at Fort Liscum is 91 inches, in 1907, but in that year Sitka had only 79 inches, or much less than the average.
It is a question whether one is warranted in drawing any definite conclusions from such iragmentary and variable statistics, but in the light of these records we cannot fail to admit at least the possibility of two conditions bearing upon the problem with which we are dealing: r(l) that there may be very extensive variations in the amount of snowfall from place to place in the Alaskan coast mountains; (2) that there may be great local variations in the amount of precipitation there from year to year.
This complicates the solution of the problem of the cause of the advancing glaciers and introduces difficulty in the definite elimination of the climatic hypothesis. Yet, in ,spite of these possible great variations in snowfall, we believe the climatic hypothesis to be inadequate to account for the spasmodic advance of the Yakutat Bay glaciers. We may perhaps best state our reasons for this belief by first considering a single one of the Yakutat Bay glaciers in comparison with the best notable known instance of glacier advance correlated with variation in snowfall, the Vernagt Glacier of the Tyrolese Alps.2 On several occasions this glacier has undergone spasmodic expansion with accompanying transformation from generally uncrevassed to crevassed condition, the last periods being in 1845 and 1898-1900.8 Although a small glacier, the Vernagt is peculiar in having a very large reservoir with a narrow ice tongue extending from it. In this way the effect of increase in snowfall is magnified and a wave of advance passing down this
i On this point, however, Dr. Cleveland Abbe writes in a letter to us under date of May 80,1910:—"I would •express my belief that the reports of rainfall at Sitka for 1882 to 1886 must be largely influenced by some temporary peculiarity in methods or gauges, or measurements. I cannot consider the excessive figures, 102 to 101 inches, as homogenous with the rest of the column for Sitka; they are not mere natural irregularities of precipitation. "
* Finsterwalder, S., Der Vernagt-Ferner, Wissenachaftliche Erganzungshefte zur Zeitschrift des D. u. O Alpenvereins, I Band, 1 Heft, Graz, 1897.
»For reference, see footnote, p. 182.